When connectivity cannot be established or is periodically interrupted, but hardware and link status is not an issue, the first place to look is at a slightly higher layer in network connections: the address resolution protocol (ARP) table. While most devices’ MAC address is bound to the hardware at the manufacturer and not easily changed, some devices have configurable or virtual MACs. In this case, you should make sure there is no conflict which could cause the IP to resolve to a different network port whenever that other device is connected to your network.

Functioning ARP is especially important in high availability (HA) topologies. If changes in which MAC address resolves to which IP address are not correctly propagated through your network, failovers may not work.

To display the ARP table in the CLI, enter: